Magnetically patterned rolled-up exchange bias tubes: A paternoster for superparamagnetic beads

We realized a deterministic transport system for superparamagnetic beads in a paternoster-like manner with position-dependent trajectories and velocities by rolling up exchange bias layer systems with engineered parallel stripe magnetic domains to tubular architectures possessing distinct azimuthally aligned magnetic domain patterns. By applying periodic pulse sequences of very weak external magnetic fields and taking advantage of the magnetic stray field emerging from the tubular structures, we demonstrate the transport for different superparamagnetic beads either in or above the rolled-up tubes acting as channels. This transport mechanism features high step velocities and remote control of not only the direction and trajectory but also the velocity of the transport without the need of fuel or catalytic material. Therefore, this approach paves the way towards novel 3D-applications in biotechnology, including particle transport related phenomena in lab-on-a chip and lab-in-a-tube devices.